MPH: Mark Hughes on...

All the evidence suggests that, during testing at Jerez last week, the big teams were brimming their fuel tanks before their long runs and keeping a decent amount on board even for short stints. The fast cars simply weren't fast enough for that not to be the case.

Last year's best time around there was a 1m17.4s, set by both Red Bull and Williams. But last week no one bettered 1m19.5s. Okay, the 2010 cars, with their bulkier tanks, probably won't be as aerodynamically efficient as their '09 predecessors, and those narrower front tyres won't have as much grip, but you can be fairly certain they're not going to be 2s per lap slower.

Fernando Alonso and Lewis Hamilton each did runs that would have required around 120kg of fuel. If you made allowance for that, they were in the high 19s-early 20s. But let's assume Ferrari and McLaren had each brimmed their tanks before those runs, squeezed in around 170kg (the widely-expected total capacity of the 2010 cars). In other words, they would still have had 50kg in their tanks when they stopped - around 1.58s worth. Then the times would make much more sense.

Having the fastest 2010 cars on low fuel capable of lapping in the high 1m17s/low 18s would tally much better, not only with the '09 times but also with the Toro Rosso's speed last week. Sebastien Buemi did the weight-adjusted equivalent of a 1m19.4s (actually a 1m20.0s, but at the beginning of an eight-lap run) - which would have put the little team's car just a couple of tenths adrift of McLaren and faster than everyone else. Doesn't quite tally, does it? But it does if you have him on genuinely low fuel and Ferrari/McLaren always with at least a spare 50kg.

It all highlights how with the no-refuelling regs, trying to read anything very detailed into the testing times is now next to impossible. And what if Ferrari was carrying an extra 50kg, but McLaren only an extra 40?

But it does figure that the big teams are so intent on getting as much heavy running as possible. Keeping the tyres in shape during the heavy-fuel first stint is going to be their key endeavour this year. The can more or less assume they're going to be fast enough to graduate to Q3, whereas the smaller teams may already have been honing qualifying set-ups in order to enhance their chances of getting out of Q1.

So it's likely the big hitters have been experimenting with different weight distributions, suspension set-ups and ride heights to work out what they can get away with. Remember that they will be qualifying a low-fuel car, but racing a full-tanked one with exactly the same set-up - because no changes are allowed post-qualifying.

That imposes tricky compromises. You could optimise your car for qualifying, grab pole, but be in a bag of handling difficulties in the race. At tracks where overtaking is particularly difficult, you might see this as a deliberate choice.

Another reason to maximise high-fuel running will be to work out how far you can trim back your front brake ducts. These extract a high aerodynamic penalty, and the smaller you make them the faster you'll be - but the greater the chances of frying your discs, especially when weighed down by 170kg of fuel. CFD teams will have been looking at ways in which the airflow to the ducts can be accelerated more, to give greater cooling for a given duct size.

Vehicle dynamacists will have been tasked with conjuring suspension geometries that allow as low a ride height as feasible in qualifying - to enchance aero performance - without it grounding out when the car's tanks are filled for the race. Building in a lot of rising rate on the rocker assembly would do that - at the front. But not at the back. Could there be a way of using that variation to good aerodynamic effect?

Here's F1 in its lab-rat phase, trying out little speed secrets for the latest set of demands, then scurrying back to modify and try again.